Which One Doesn't Belong? Fraction Addition Models

Look at this set of four pictures. Decide which one doesn’t belong with the other three. Use math words to describe your thinking. There are many ways to think about each one!

A. shows 9-eighths + 1-eighth + 1-fourth. B. shows 2 analog clocks. One clock is shaded red and 5 of 6 parts on the other are red. 2 of the shaded parts are crossed out. 1 and 5-sixths minus 1-third. C. shows a model with 3 of 4 parts shaded green. Another model shows 6 of 8 parts shaded blue. 3-fourths + 6-eighths. D. shows a money model with 8 dimes plus 5 dimes. 8-tenths + 5-tenths.


Find reasons why each of the pictures might not belong with the other three.


Explain your thinking to someone else. Do they have different reasons why one doesn't belong?